Heart valves are sometimes damaged by disease or by aging, resulting in problems with the proper functioning of the valve. Heart valve replacement has become a routine surgical procedure for patients suffering from valve dysfunctions. Traditional open surgery inflicts significant patient trauma and discomfort, requires extensive recuperation times, and may result in life-threatening complications.
To address these concerns, efforts have been made to perform cardiac valve replacements using minimally-invasive techniques. In these methods, laparoscopic instruments are employed to make small openings through the patient's ribs to provide access to the heart. While considerable effort has been devoted to such techniques, widespread acceptance has been limited by the clinician's ability to access only certain regions of the heart using laparoscopic instruments.
Still other efforts have been focused upon percutaneous transcatheter (or transluminal) delivery and implantation of replacement cardiac valves to solve the problems presented by traditional open surgery and minimally-invasive surgical methods. In such methods, a stented prosthetic heart valve is compacted for delivery in a catheter and then advanced, for example through an opening in the femoral artery, and through the descending aorta to the heart, where the stented prosthetic heart valve is then deployed in the valve annulus (e.g., the aortic valve annulus).
Various types and configurations of stented prosthetic heart valves are available for percutaneous valve replacement procedures. In general, stented prosthetic heart valve designs attempt to replicate the function of the valve being replaced and thus will include valve leaflet-like structures. Valve prostheses are generally formed by attaching a bioprosthetic valve to a frame made of a wire or a network of wires. Such a stented prosthetic heart valve can be compressed radially to introduce the stented prosthetic heart valve into the body of the patient percutaneously through a catheter. The stented prosthetic heart valve may be deployed by radially expanding it once positioned at the desired treatment site. If the deployed prosthesis is incorrectly positioned relative to the valve annulus, serious complications may arise, including paravalvular leakage (PVL) or the requirement for placement of a permanent pacemaker.
A standard delivery device for percutaneous transcatheter delivery of a stented prosthetic heart valve is shown in FIGS. 1A-1C. FIG. 1A shows a delivery device 1100 in a delivery configuration. FIG. 1B shows delivery device 1100 with a capsule 1108 retracted. FIG. 1C shows planer or longitudinal movement of capsule 1108 of delivery device 1100. Delivery device 1100 includes a handle 1140, an outer stability shaft 1110, a proximal shaft 1118 coupled to capsule 1108, and an inner shaft 1114. A stented prosthetic heart valve (not shown) in a radially compressed delivery configuration is compressively retained within capsule 1108 for delivery to the treatment site. A gap distance G1 is the distance between a distal end 1126 of outer stability shaft 1110 and a proximal end 1109 of capsule 1108. Gap distance G1 is required to permit retraction of capsule 1108, along a longitudinal axis LAd, to fully release the stented prosthetic heart valve (not shown) as shown in FIG. 1B. Gap distance G1 plus the length of capsule 1108 combine to form a lever arm L1, as shown in FIG. 1A. Stated another way, lever arm L1 includes gap distance G1 and the length of capsule 1108 and extends from distal end 1126 of outer stability shaft 1110 to the distal tip of delivery device 1100.
Prior to release of the stented prosthetic heart valve (not shown) at the treatment site, it may be desired to adjust the centered position of capsule 1108 in relation to a valve annulus utilizing a steering mechanism 1152 of delivery device 1100. Steering mechanism 1152 is actuated with a steering actuator 1148 of handle 1140, as shown in FIG. 1C. However, lever arm L1 may result in an inaccurate or unpredictable steering of capsule 1108 and stented prosthetic heart valve retained therein. More particularly, small movements of steering actuator 1148, combined with the relatively long length of lever arm L1, translate to a relatively large planar movement PMI1 or PMr1 and a large deflection distance Dd1 from longitudinal axis LAd, of capsule 1108 and stented prosthetic heart valve retained therein.
Accordingly, there is a need for an improved delivery device design and methods to provide smaller centering adjustment movement of capsule 1108 for more accurate positioning of a stented prosthetic heart valve to reduce the instances of post procedure complications.